Aeroplane propeller or the like



0. A. ROSS. AEROPLANE PROPELLER 0R THE LIKE. APPLICATION FILEDsEPT.1'4,1917.

1,40225 39, Patented Jan. 3, 1922o UNITED STATES r-ATENT OFFICE..

OSCAR A. ness, or New YORK, `1v. y.

PROPELLER THE LIKE.

To @ZZ/whom it may concern.'

Belt known thaty I, OsoAn A. Ross, a citizen of the United States ofAmerica, re.-

siding at 115 Carnegie Hall, New Yorkcity,

county of New York, State of New York, have invented a new and usefulImprovement in Aeroplane Propellers or the like, yof which the followingis a specification.

Thispinvention upon which is based my present application for LettersPatent pertains to air pro'pellers, or screws for aeroplanes. They areemployed preferably in connection with that class of aeroplanes known asthe tractor type. My invention has for its more prominent objects theattainment in a more economical and effective manner of the results, oryoperations hereinafter specified.

Primarily the purpose in view is to permit propellers to be operated ata much higher rotative speed than those now in common use. At thepresent time the limit of rotative speed of propellers is such thatgearing is interposed between ythe motor'and propeller to V`permitobtaining maximum etliciency from the motor, the' motor runningconsiderably faster than the propeller. lt

is evident that this 'gearing entails a loss of power, adds weight andis otherwise objectionable.

A further object is to furnish a shield formed with a streamline surfacefor the center portion of the propeller, such, that the air at thecenter of the propeller will be forced out into the maximum torqueproducing portion of the blades thereby forming a dense, compact columnof air for the efficient portion of the blades to work in. It is a wellknown fact that with an 8 to 9 foot diameter propeller in excess of 90per cent of the torque is obtained in the last 18 to 24 inches of theblade.

All the above and other objects sought are attained by the propeller,which for purposes of specific illustration, is shown in theaccompanying drawings, in which- Figure 1, is a plan View of my improvedpropeller looking at lthe forward end of an aeroplane.

Figure 2,1is a side velevation of Figure 1.

Figure 3, is a modification of means to reenforce the propeller bladeshown in Figures 1, and 2.

Figure 4, is a diagrammatic illustration of stresses in my improved formof propeller in action.

ySpseither-ition of Letters lvatent. y Patnted Jan, 3 1922,` Applicationfiled September 14, 1917. Serial 1No. 191,438'. i i

propeller, are, or need be, of any special' or unusual construction, butfor amore .ready understanding Vof the devicek and of its operation, apreliminary description of the construction maybe apposite. V

Referring to Figures 1, and 2,r 1 1, are

the propelling portionsy of theV propeller blade 2. The circular sectors3 3, may `be integral or secured to the blade in any approved manner, asfor example, gluing land dowelling. The hub 4, with flange 5,:and bolts6,3form the unit for securing the propeller to the motor of theaeroplane.V

The shield formedwith a streamline surface 7, of cone like constructionis secured in place by screws 8, and is notched on oppositesides toreceive the blade 2. Reinforcing, or bracing members 10, are preferablyfitted, glued and dowelled tothe center section 2, screws 12, assistingin securing said members to the said center section'.y Cross f members9,V serve to prevent members `10,.

from"`bu'lckling, yor springing as lstrains, 'are placed upon them byspringing, or bending of the propeller ends 1 1, as will more fully behereinafter described. Screws 11, are

shown as the preferable means for securing to Figure 5, the solid lineS, represents the mean radial axis of a propeller of ordinary design,rotating on axis A. The distance H,

`represents the nominal hub `diameter of the propeller and, therefore,assuming that the machine to which the propeller is attached istraveling in the direction of arrow W, the deflection of the propellerblades will be substantially in accordance with dotted line D. Thedotted line T and arrows 16, represents the circumferential plane inwhich the maximum torque is produced by Athe propeller. It is evidenttherefore, that CIA sents the characteristics of the inventorspropeller, it is noted that the leverage F, is relatively small ascompared with E, of Figure 5, therefore the bending moment at Y, is muchreduced for a similar rotative speed of compared propellers andobviously permits of a much higher speed with the applicants propeller.The hub vdiameter in applicants propeller is practically represented bythe distance G, the center section 2, with reinforcing members 9, andl0, forming a rigid unyielding structure.

As stated hereinbefore, practically all the torque developed by anaeroplane propeller is obtained from the outer one half ofthe blades.VOwing to a factor known generally as the slip, said slip being due tohead resistance, etc., a propeller never travels progressively at thetheoretical speed calculated from its pitch. For this reason theair isalways tending to be drawn into the blades. This causes a partial vacuumin front of the propeller again tending to develop churning, of the airthereby reducing the eiiiciency and resulting torque. In

my improvedv propeller, thevshield formed with a streamline surface 7,forces the oncoming air in the direction of arrows l5, to the outer halfof the blade thereby forming a dense, compact column of air for theeiicient part of the blades to work on.

From all investigations conducted by the vinventor vit appears that thebest ratio of shield formed with a streamline surface and propellerdiameters are substantially as l, is to 2. Thatis the shield at itsgreatest diameter should be substantiallyy one half the diameter of the.propeller.

Although I Ahave herein shown and described only certain forms of myinvention, it is understood various changes and modications may be madetherein without departing from the spirit of the invention.

What I claim is 1. In combination with an aeroplane propeller, a shieldformed with a streamline surface attached theretoV and means forreinforcing said propeller, said means being contained within theperipheral surface of said shield substantially as described. Y

2. In an aeroplane driving means, in combination: a propeller; ashieldformed with a* streamline surface located forwardly of thepropeller; meansto support the shield,

and reenforcingmeans for the propeller 4located rearwardly of theshield.

In testimony whereof, Oscar A. Ross, has signed his name to thisspecification in the presence of two subscribing Witnesses, this 18thday of August, 1917.

OSCAR A. ROSS.

